The Exeter forward, who captained Wales in last season’s Six Nations, underwent knee and shoulder surgery during the summer.
But while Chiefs’ England centre Henry Slade is on course to return after a shoulder operation in the next month, Jenkins is slightly behind that rate of progress.
“He (Jenkins) is probably the guy who is behind the others – Henry and Tommy Wyatt – at getting back in that Premiership Cup period (November 1-22),” Exeter rugby director Rob Baxter said.
“Not because of anything other than he had the two operations – knee and shoulder – and they don’t complement each other massively when you are talking about rehab.
“Each one limits the other a little bit. Having said that, Daf is one of those guys who has always been a great trainer, and he is just the same in rehab.
“If anyone is going to get back soon or on time from an injury, it’s going to be Daf.
“If he can make the tail-end of the Premiership Cup, that would be fantastic, but he is not quite at the level where the other two are.
“The other guys we are expecting to see them in the Premiership Cup period being available, but he may be that little bit behind.”
Wales have lost their last nine Tests and kick off their autumn programme against Fiji on November 10, which is followed by appointments with Australia and South Africa.
The absence of Jenkins gives the Dragons duo of Ben Carter and Matthew Screech a chance to stake a claim after going on tour last summer.
The pair joined forces in the Twickenham Test against South Africa but injury denied Dragons captain Carter the chance to add to his caps against the Wallabies.
He also sat out the friendly against Queensland Reds when Screech joined Jenkins in the boilerhouse.
Warren Gatland selected Jenkins and Exeter teammate Christ Tshiunza as his starters in the Tests when Cory Hill came off the bench.
Adam Beard missed the tour through injury but has returned to action with the Ospreys.
